In order to acquire images under magnification, such as in-line holograms, an optical point source may be required. For example, it is known in the art to provide a high quality point source by using a high numerical aperture (NA) objective focused on a pinhole. However, this may require a large optical set-up, which may be expensive and difficult to scale down. Therefore, scalable, micrometer size alternatives may be advantageous. Such scalable alternatives may be used in applications where a large number of objects are to be imaged simultaneously, for example in parallel on-chip holography.
It is known in the art to use a pulled fiber having a very small core diameter to create a high NA light cone with a substantially uniform spherical wavefront. However, a higher level of on-chip integration may be advantageous in semiconductor photonics, e.g. due to the implied cost reduction, manufacturing efficiency and scalability.